OK so i have searched all over for info, but I have not come across anyone who has fixed this problem.. I do keep hearing about this problem alot!

I have a 98 blazer, heat works fine everwhere, except floor. NOTHING blows out the floor vent. If I put it on floor, it blows out the dash. Yeah there is a tsb on it, but what do I do next??? Thanks

TSB #010138008 -- SOME CUSTOMERS MAY COMMENT THAT THE HVAC SYSTEM IS NOT WORKING CORRECTLY. WHEN THE CONTROL IS MOVED TO THE DOWN OR FLOOR (HEAT) POSITION, AIR CONTINUES TO FLOW FROM THE END VENTS OF THE DASH. NLM (NHTSA ID #622702, JUNE 01 2001)

The actuator that controls this valve (foam panel) is located to the right of the gas pedal, it has a white arm with red and blue vacuum lines going into it. You can't miss it.

It isn't that actuator that breaks, it is the valve (foam panel). You can see why once you have the whole thing back together; the actuator puts pressure on the valve, forcing it to bend. I’m sure it breaks quite easily when it is extremely cold out.

some say you can fix without pulling the dash, but i personally think it was easier to just pull the dash and get errrrr done.

now that ive done this, i'd be happy to fix it for someone else $$$$$$$$$$$$ pain the the ass
****ALSO MIGHT I RECOMMEND- DO NOT USE FULL DEFROST(meaning defrost only). USE DEFROST/FLOOR setting.. when using full defrost, this position has the actuator put a sh(T ton of stress on the plastic arm on the foam panel... you can see it actually bend when you put full defrost on. whether you have fixed it.. or if it has never broken, it will break eventually.. it puts way too much stress on a piece of plastic. see for yourself. switch through the controls and watch the piece bend when you put full defrost on.. ****

That is right, it is the little door in the heater box. I am going to have to fix this on my 97 S-10 as well as my son's 2000 Blazer. Does anyone have pictures or can tell me what all needs to be taken apart on the dash to get down to the heater box. I can see it but it looks like a lot of stuff needs to come out to get to it.

edit this is not a pic of the floor/face control..it is the defrost control... the one above with the yellow and brown is the right one

What you're looking at is directly to the right of the gas pedal, on the floor. From what I understand, the round black thing with the red & blue vacuum lines going into it is the floor setting actuator. I'm assuming the white thing right above it is the end of the door that controls the airflow to the floor vents.
Couple questions:

1) Is everything I said above correct?

2) How exactly do I get to the door that controls airflow to the floor? Do I have to take more parts out, to get to it?

3) When I tried to move the white part with my hand, I still couldn't feel any heat coming out of the floor. Does that mean I 100% have the problem with the vent door?

I am replacing this heater door right now. The part number you need is 52470781, it costs around 20 dollars. You will have to take the dash all the way out to get to where you can access this. You will have to take the spring clip off the actuator and a screwdriver will pop off the little white control piece that has the spring on it. I will write back tomorrow after I buy the door and reinstall it and let you know if I hit any snags. By the way once this door is broken you can move that little white arm all you want and it will not change your heat direction. It is broken inside the heater box clean through.

Just finished replacing heater door. No problems, did not have to take heater box apart. You will want to buy the little white plastic lever that you can see without taking the dash apart. It has the little spring on it. The part No. is 52487574 it costs about $3.00. The dash goes back in a lot faster than it comes out. I am sure glad I don't have to replace the heater core, but I would not be afraid to tackle it now that I have had the dash out. This wasn't as bad as replacing the clutch slave cylinder.

Just finished replacing heater door. No problems, did not have to take heater box apart. You will want to buy the little white plastic lever that you can see without taking the dash apart. It has the little spring on it. The part No. is 52487574 it costs about $3.00. The dash goes back in a lot faster than it comes out. I am sure glad I don't have to replace the heater core, but I would not be afraid to tackle it now that I have had the dash out. This wasn't as bad as replacing the clutch slave cylinder.[/quote]

Can you tell me what to look for to tell if this heater door is broken? What all do you have to take apart to get this door replaced? Thanks Steve.

Well I checked the vacuum actuator thing with a vacuum gauge and it works 100% and I looked at the door control again and it seems very loose. So I'm guessing the door is broke. Does anyone know how to check this and repair this??

I'm having a problem with no floor heat on my 03 Blazer and hope someone can help me out. Actually there is some coming out the floor vents like there should be on the vent setting but it seems to be stuck on that setting. If I close all the vents on the dash it works just fine as far as getting enough floor heat.

I guess my question is if I should be able to hear something/anything if the door is broken? With the engine just shut down I can't hear anything when I move the selector. I would think I would at least be able to hear something moving/making some type of sound. No vacuum or mechanical noises at all. No matter where I move the selector it doesn't seem to make any changes but it does shut down the blower motor when I select "off".

I just bought this truck about a month ago and it always took 15 seconds or so to switch from vent to floor but all of a sudden one day it just quit altogether. I looked around some under the hood at the vacuum lines but they didn't seem dry or cracked at all. I haven't pulled the under dash panel yet to look at the actuator but when I was looking under the dash I did find a piece of foam rubber about 1/2" X 1/2" and 5" long stuck in the opening of the floor vent. Is this a sign of a broken door? I hope not! Sounds like an expensive fix.

Thanks to all of you for your advice on how to fix this problem, especially to greatjc for posting the picture. This is exactly the problem I'm having. A few questions, though:

1. Is it possible to fix the broken arm/door without pulling dash? If so, could someone post the steps to do it (pictures would be great!).

2. If I really have to pull the dash (grumble, grumble), how do I do that? I need step by step instructions, preferably with pics. Online would be good, but I can buy a manual if need be. Which manual is best?

OK, so here is what happened to my truck:

1998 Jimmy
125,000 miles

Truck was cold soaked at 0 degrees. Started it up, blower was on high, temp control on hot, climate control on heat (feet). Like a **DUMMY** , I switched the climate control to defrost. I knew as I did it that I should have waited for things to warm up a bit. I heard the baffle/door groaning from beneath the defroster vents as it slowly moved, then **SNAP** something let go under there. Now on defrost, defrost & heat, and heat it just blows up through the defrost vents onto the windshield. On vent it blows through the dash vents and not through the defrost vents--must be a separate baffle/door?

I'm having a problem with no floor heat on my 03 Blazer and hope someone can help me out. Actually there is some coming out the floor vents like there should be on the vent setting but it seems to be stuck on that setting. If I close all the vents on the dash it works just fine as far as getting enough floor heat.

I guess my question is if I should be able to hear something/anything if the door is broken? With the engine just shut down I can't hear anything when I move the selector. I would think I would at least be able to hear something moving/making some type of sound. No vacuum or mechanical noises at all. No matter where I move the selector it doesn't seem to make any changes but it does shut down the blower motor when I select "off".

I just bought this truck about a month ago and it always took 15 seconds or so to switch from vent to floor but all of a sudden one day it just quit altogether. I looked around some under the hood at the vacuum lines but they didn't seem dry or cracked at all. I haven't pulled the under dash panel yet to look at the actuator but when I was looking under the dash I did find a piece of foam rubber about 1/2" X 1/2" and 5" long stuck in the opening of the floor vent. Is this a sign of a broken door? I hope not! Sounds like an expensive fix.

Thanks in advance.....Barry

I ended up taking my truck to a Chevy dealer for repair. Luckily, it wasn't the door. Instead it was an actuator, Part #52494116 "mode valve actuator". Now it switches modes right away instead of taking 15 seconds or so. They weren't sure where the piece of foam I found came from. I'd guess it was a piece of a door seal from inside the heater box. Cost was $210, not cheap but cheaper than the 7 hours and $650 I was quoted for replacing a broken door!

It sounds like you have a different problem though scrnchr. Good luck.

thanks for the updatey, mrmaico. did they tell you where that actuator is mounted? maybe something i could check for.

i'm in a catch22, it's been too cold here to work on it, and so the cold freezes my feet........

I didn't ask where it was located but I did take a look inside while they waited a day for the part to show up and I do know it wasn't the one just to the right of the accelerator pedal. It looked to me like it probably would be located just to the right of center. That's just a guess though. They did have both the center and right side under-dash panels off to get at it.

I'd say for people that have a slow-to-respond control as far as changing where the air is blowing from that quits working altogether it would be a good bet to check this actuator before tearing out the dash to get at a broken door.

scrnchr - it sounds like your heater door's broken. That's exactly what mine did - no air comes through the floor, so the system automatically switches to defrost (because the air has to go
somewhere). There's a TSB out there about the problem, but I think it's listed for a Tracker. Your local GM dealer should have it. I ran through the troubleshooting steps first, to make sure it
wasn't anything else causing the problem.

I did mine in the fall (2001 Blazer), and it took me maybe a week of on & off work. I probably only worked on it an hour or two a day, but it's still a pretty long job. I didn't take pictures of
my progress, and my memory about the process isn't 100%. I'll give you some pointers, from what I do remember:

1. Yes, the dashboard will need to come out. The whole thing. From the windshield to the steering wheel. Any attempts to shortcut this will just end up taking longer. Trust me on that one.
Just suck it up & get down to business.

2. Go to your local library and look for the Factory Service Manual for your Jimmy. The steps are not in order, so I'd follow along in the book & write a note with the page numbers in the order
you'll need to follow (e.g. You'll see a lot of "refer to X Removal Process section for X removal"). The FSM steps have (some) pictures, and the process is fairly intuitive.

3. I didn't have to pull my steering wheel, but I did drop the column. If I did this again, I probably would've removed the wheel for more clearance. I ended up with a scratch on my steering
wheel when getting my dash back on. If you've got one of the models with the bigger steering wheel, I'd consider removal to be a requirement. At some points, I put the parking brake on & moved the column shifter all the way down, to get more clearance on the top of the column.

4. You'll want to do the work in a place where you can open both doors & have 1-2 feet of clearance beside each open door. The worst thing that could happen is to get the dashboard removed &
find you don't have enough room to get it out of the truck.

5. You might also want to remove the A-pillars (very easy - they pull off) & throw a towel over anything you think you might scratch if the dashboard slips. There is metal protruding from
the rear of the dash, and it's fairly easy to put a deep scratch in paint or an interior panel.

6. Your 3 best friends in this endeavor will be: box of Ziploc sandwich bags, roll of masking tape, Sharpie. After I took a part out, I put the screws to that part in a Ziploc bag, wrote
the name of the part & the side of the truck it came out of on the bag, and taped the bag of screws to the part that came out. If you need a diagram of how the part goes in or where the screws go, write yourself a note & throw it in the bag. There will be a lot of screws coming out. A LOT. Knowing where they go is WELL worth the extra time in labeling.

7. Same goes with the electrical connectors. All of the wires in my Blazer's dashboard come from the fuse box on the left, and the main wire bundle runs down a plastic center channel bolted to the back of the dashboard. Don't try to take the plastic channel out - just cut the electrical tape holding the wire bundle. When I put the bundle back in, I used zip ties to get it back in the
channel. I also wrapped another layer of electrical tape around the bundle, just for the hell of it.

8. Label every single electrical connector that comes out. I didn't, and I regret it. You'll be amazed at how many of them there are. Also label where the connector goes on the dash. If you
want to take pictures to remind you later on, now's the time to do it. Take my advice on this one - I ended up spending over an hour on taking parts back out because I thought I forgot to hook up my passenger side door jamb interior light switch. As it turns out, I had to trace the wiring diagram to find out my Blazer doesn't have one of those (it's controlled by the exterior door handle). There was a connector, and a switch, but no wire. Learn from my mistake. Label your connectors.

9. If your dashboard speaker covers have screws like mine, you'll want to use something like this: http://www.harborfreight.com/cpi/cta...emnumber=92630. I don't even think
there's enough room to get a stubby screwdriver in there, so that right angle driver is a lifesaver.

10. The top of the dashboard rolls forward, then lifts up. There's a J-shaped metal part on the bottom which goes around a peg coming from the body. You need to tilt the dashboard forward, so
the J clears the peg. You should be able to see it at the bottom of the dashboard assembly, above the kick panels. I think I ended up removing the kick panels when the dashboard went in, so I could see the pegs a little better.

11. The dashboard is difficult to maneuver, and it's a little heavier than I expected. Put both of your front seat/seatbacks all the way back, open the passenger side door all the way, and move
it out through the passenger door. If you have a helper on the driver's side or have removed the steering wheel, this step will be exponentially much easier. Since I did mine solo, I slid the
driver's seat all the way forward, to prevent the steering column from dropping too far down if I happened to drop the dash.

13. See the compartments in the middle with the foam around them? The heater door is in there. It will probably move back & forth easily with your hands, because the plastic at one of the
ends is snapped. If the part is completely intact, you should probably start swearing loudly now.

14. If I were you, I'd take a picture or draw a diagram of the way the door tab fits on the spring, on the left side of the heater box (on the outside). If I remember right, there was a little
trick to it. The door will take a little maneuvering to get in & out of the box, but just be patient & use your head. It's not really difficult.

15. Everything goes back in pretty much the way you'd expect it to. If you labeled everything like I recommended, this should be cake. The only tricky part I ran into was lining the dashboard
up with the screws on top. I took a straightened paperclip to poke threw the screw holes in the dashboard, to make sure they lined up with the screws on the body. If you can see in my picture,
the black rubber "flap" tends to cover the screw hole a bit, when the dash is on. I don't think there would be any harm in trimming it a bit so it doesn't cover the hole.

16. After you've got most of the electrical connectors hooked up & the dash in place, it would be a good time to pause. Start the car, so you can check your heater settings & other switches. In
the unlikely case you screwed something up, you want to know before you've tightened everything down.

17. Everything works? Awesome. Continue putting everything back where it belongs. When it's all back in, do one final test of all the dashboard switches, then bask in the glory of your
accomplishment.

If I remember right, you can't reach the door without removing the dashboard. And if you're removing the dash, you might as well just replace the door.

The vents in the center of the dashboard don't lead directly to the heater box door. There is a network of ducting carrying the air through the vents. Also, you can't just manually push on the actuator arm to lift the door, since the plastic usually breaks right after the part that contacts the actuator (which is why the door won't open in the first place).

ok so i got under my dash to take a look at things and if i move the arm for the flap my heat goes to the floor if i push it away from the firewall and it goes to the face if i push it to the firewall...i took off both the brown and yellow tubes and both get the correct vacuum when they need to i think

so i figured there is now way i am pulling that dash for heat so i figured i would redneck fix it..lol

before..

after...with heat on the feet

in summer time i will cut the wire tie...and maybe push it forward for all air to the face...but i dont care...lol

hardest part is getting that push rivit off without breaking the white lever.. its cake if you take out your glovebox... had similair issues this weekend on my buddies jimmy.. after we did the heater core i forgot to hook up one of the lines.. simple fix..

hardest part is getting that push rivit off without breaking the white lever.. its cake if you take out your glovebox... had similair issues this weekend on my buddies jimmy.. after we did the heater core i forgot to hook up one of the lines.. simple fix..

glove box???? the one in my picture is under the dash to the right of the gas pedal..

The FSM says the actuator just pulls out. It looks like it's held in by some retaining tabs, so it should just come out by pulling it towards the driver's side. After disconnecting the vacuum lines from the actuator body and the actuator arm from the retaining clip/spring, of course.

This is great, guys. Pretty soon I need to wedge my big arsh in front of the seat and get my fat head up under my dash to see what went wrong. All of your discussion and especially your pictures are really helping to edumacate me in advance! Thanks for that.

This is great, guys. Pretty soon I need to wedge my big arsh in front of the seat and get my fat head up under my dash to see what went wrong. All of your discussion and especially your pictures are really helping to edumacate me in advance! Thanks for that.

yeah.. i had to move the seat way back..and it dont help that the truck is lifted and i had no way of supporting my weight...plus i kept dropping my led drop light and it always ended up facing me right in my eye..blinding me..hahah

Actually I've got a replacement driver's seat that I need to install anyway, so I might pull the seat and look under the dash that way. I'd like to beef up the frame of the seat I'm putting in, because my big body keeps bending up the dam seat frames (they collapse toward the floor and the seat back leans backward due to bending of the lower frame). Definitely not trying to hijack this thread, but if someone can point me to a thread on strengthening the seat frame that'd be great. With the seat out, I can lay some old couch cushions in there and lay flat on my back to work under the dash. I sure hope mine's an easy fix or that I can rig it to split the heat between the defrosters and heat, because I sure don't want to pull the dash!

more than 260. offensive lineman. 6' 4" tall, plenty of muscle, now have the optional beer gut. the seat in my yukon xl is rock solid. had a dodge conversion van with flexsteel seats, those were the greatest. i also broke a drivers seat on a grand prix, but that was like a '79 and i was at playing weight. i have a tendency to stretch in the seat and end up pushing too hard on the seat back.

i work on my jimmy because i don't want to pay someone to work on my 11 year old truck. it's a great second truck, does ok with 4wd in the snow.

more than 260. offensive lineman. 6' 4" tall, plenty of muscle, now have the optional beer gut. the seat in my yukon xl is rock solid. had a dodge conversion van with flexsteel seats, those were the greatest. i also broke a drivers seat on a grand prix, but that was like a '79 and i was at playing weight. i have a tendency to stretch in the seat and end up pushing too hard on the seat back.

i work on my jimmy because i don't want to pay someone to work on my 11 year old truck. it's a great second truck, does ok with 4wd in the snow.

no shit.. i know nothing about sports and shit but do you play for a major team?

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